fs/squashfs/xattr_id.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Squashfs - a compressed read only filesystem for Linux
   4  *
   5  * Copyright (c) 2010
   6  * Phillip Lougher <phillip@squashfs.org.uk>
   7  *
   8  * xattr_id.c
   9  */
  10
  11 /*
  12  * This file implements code to map the 32-bit xattr id stored in the inode
  13  * into the on disk location of the xattr data.
  14  */
  15
  16 #include <linux/fs.h>
  17 #include <linux/vfs.h>
  18 #include <linux/slab.h>
  19
  20 #include "squashfs_fs.h"
  21 #include "squashfs_fs_sb.h"
  22 #include "squashfs.h"
  23 #include "xattr.h"
  24
  25 /*
  26  * Map xattr id using the xattr id look up table
  27  */
  28 int squashfs_xattr_lookup(struct super_block *sb, unsigned int index,
  29                 int *count, unsigned int *size, unsigned long long *xattr)
  30 {
  31         struct squashfs_sb_info *msblk = sb->s_fs_info;
  32         int block = SQUASHFS_XATTR_BLOCK(index);
  33         int offset = SQUASHFS_XATTR_BLOCK_OFFSET(index);
  34         u64 start_block;
  35         struct squashfs_xattr_id id;
  36         int err;
  37
  38         if (index >= msblk->xattr_ids)
  39                 return -EINVAL;
  40
  41         start_block = le64_to_cpu(msblk->xattr_id_table[block]);
  42
  43         err = squashfs_read_metadata(sb, &id, &start_block, &offset,
  44                                                         sizeof(id));
  45         if (err < 0)
  46                 return err;
  47
  48         *xattr = le64_to_cpu(id.xattr);
  49         *size = le32_to_cpu(id.size);
  50         *count = le32_to_cpu(id.count);
  51         return 0;
  52 }
  53
  54
  55 /*
  56  * Read uncompressed xattr id lookup table indexes from disk into memory
  57  */
  58 __le64 *squashfs_read_xattr_id_table(struct super_block *sb, u64 table_start,
  59                 u64 *xattr_table_start, unsigned int *xattr_ids)
  60 {
  61         struct squashfs_sb_info *msblk = sb->s_fs_info;
  62         unsigned int len, indexes;
  63         struct squashfs_xattr_id_table *id_table;
  64         __le64 *table;
  65         u64 start, end;
  66         int n;
  67
  68         id_table = squashfs_read_table(sb, table_start, sizeof(*id_table));
  69         if (IS_ERR(id_table))
  70                 return (__le64 *) id_table;
  71
  72         *xattr_table_start = le64_to_cpu(id_table->xattr_table_start);
  73         *xattr_ids = le32_to_cpu(id_table->xattr_ids);
  74         kfree(id_table);
  75
  76         /* Sanity check values */
  77
  78         /* there is always at least one xattr id */
  79         if (*xattr_ids == 0)
  80                 return ERR_PTR(-EINVAL);
  81
  82         len = SQUASHFS_XATTR_BLOCK_BYTES(*xattr_ids);
  83         indexes = SQUASHFS_XATTR_BLOCKS(*xattr_ids);
  84
  85         /*
  86          * The computed size of the index table (len bytes) should exactly
  87          * match the table start and end points
  88          */
  89         start = table_start + sizeof(*id_table);
  90         end = msblk->bytes_used;
  91
  92         if (len != (end - start))
  93                 return ERR_PTR(-EINVAL);
  94
  95         table = squashfs_read_table(sb, start, len);
  96         if (IS_ERR(table))
  97                 return table;
  98
  99         /* table[0], table[1], ... table[indexes - 1] store the locations
 100          * of the compressed xattr id blocks.  Each entry should be less than
 101          * the next (i.e. table[0] < table[1]), and the difference between them
 102          * should be SQUASHFS_METADATA_SIZE or less.  table[indexes - 1]
 103          * should be less than table_start, and again the difference
 104          * shouls be SQUASHFS_METADATA_SIZE or less.
 105          *
 106          * Finally xattr_table_start should be less than table[0].
 107          */
 108         for (n = 0; n < (indexes - 1); n++) {
 109                 start = le64_to_cpu(table[n]);
 110                 end = le64_to_cpu(table[n + 1]);
 111
 112                 if (start >= end || (end - start) >
 113                                 (SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
 114                         kfree(table);
 115                         return ERR_PTR(-EINVAL);
 116                 }
 117         }
 118
 119         start = le64_to_cpu(table[indexes - 1]);
 120         if (start >= table_start || (table_start - start) >
 121                                 (SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
 122                 kfree(table);
 123                 return ERR_PTR(-EINVAL);
 124         }
 125
 126         if (*xattr_table_start >= le64_to_cpu(table[0])) {
 127                 kfree(table);
 128                 return ERR_PTR(-EINVAL);
 129         }
 130
 131         return table;
 132 }